JP2000153770A - Electric power steering unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hunting when a main control unit error occurs by prohibiting motor drive with a latch device when a drive prohibition judgement device judges that the motor drive status is in the prohibited range. SOLUTION: When an error occurs at an main control unit 20, if the drive status of a motor 6 goes into the prohibited range, for example because the steering wheel is turned abruptly in the opposite direction, it is judged in the motor drive prohibition judgement portion 31 that the drive status of the motor 6 is in the prohibited range. A flip-flop 32b maintains the H level. Drive of the motor 6 is prohibited by setting the output IL from the sub control unit 30 to the L level. Accordingly, until the main control unit 20 stops output of drive signals to the motor 6, an interlock can be maintained by the sub control unit 30, and this makes it possible to prevent hunting when an error occurs at the main control unit 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering system in which a malfunction of an interlock function hardly occurs.

[0002]

2. Description of the Related Art FIG. 15 is a block diagram conceptually showing the structure of a conventional electric power steering apparatus. FIG.
As shown in FIG.
The vehicle includes a steering torque sensor 1, a main control device 2, a sub control device 3, a motor drive circuit 4, a motor current detection circuit 5, and a motor 6.

[0003] As shown in FIG.
Are connected to the input terminals of the main control device 2 and the sub control device 3. The output terminals of the main control device 2 and the sub control device 3 are connected to a motor drive circuit 4, and a motor 6 is connected to the motor drive circuit 4.
Further, a motor current detection circuit 5 for detecting a current supplied to the motor 6 is connected to the motor drive circuit 4, and an output terminal of the motor current detection circuit 5 is connected to the main control device 2 and the sub control device. 3 respectively.

In such an electric power steering device, a steering torque T detected by a steering torque sensor 1 is transmitted to a main control device 2, and the main control device 2 transmits the steering torque T via a motor drive circuit 4 based on the steering torque T. , Motor 6
Is driven to assist the steering force of the driver.

[0005] The steering torque sensor 1 is connected to a steering device (not shown), and detects a driver's steering torque input to the steering wheel and outputs it as a voltage value (steering torque signal). FIG.
FIG. 4 is a characteristic diagram illustrating a relationship between a steering torque detected by a steering torque sensor and a steering torque signal output by the steering torque sensor.

When the neutral position of the steering torque sensor 1 is normal (that is, when there is no deviation), the characteristic shown by the solid line in FIG. 16 is obtained, and the steering torque T becomes 0 (kgf ·
In the case of m), the value of the steering torque signal output by the steering torque sensor 1 is 2.5 (V). The value of the steering torque signal increases when the torque for steering the steering wheel to the right increases (maximum value 5 V), and decreases when the torque for steering the steering wheel to the left increases (minimum value). 0V).

The sub controller 3 is provided for monitoring a failure of the main controller 2.
It has an interlock function. Such an interlock function is provided to avoid a dangerous state even when an abnormality (an abnormality due to noise, an abnormality due to a failure, or the like) occurs in the drive state of the motor 6 by the main control device 2. For example, the driving state of the motor 6 is shown in FIG.
When you enter the prohibited area shown in, the interlock is activated,
The operation of the motor 6 is prohibited. As described above, the conventional electric power steering apparatus has the interlock function, and is designed so that the driving state of the motor 6 does not become abnormal.

[0008]

As described above, in the conventional electric power steering apparatus, when the driving state of the motor 6 enters the prohibited area, the interlock is activated to cut off the motor current. When the motor current is cut off, the motor 6
Is out of the prohibited area, the sub-control device 3 releases the interlock.

However, the cause of the operation of the interlock is as follows.
If the main control device 2 is out of order, the driving state of the motor 6 enters the prohibited area again even if the interlock is released, and the hunting phenomenon occurs due to the operation of the interlock again. was there.

[0010] Accordingly, an object of the present invention is to provide an electric power steering device that ensures a high degree of safety by suppressing erroneous operation of an interlock.

[0011]

An electric power steering apparatus according to the present invention includes a steering torque detecting means for detecting a steering torque inputted to a steering wheel, and a motor based on a steering torque detected by the steering torque detecting means. A main control device for controlling driving; a sub-control device for monitoring the main control device; and a motor driving means for driving a motor based on outputs of the main control device and the sub-control device. A driving prohibition determining unit that determines a state; and a latch unit that holds a first determination result of the driving prohibition determining unit. Set prohibited areas to be prohibited,
Determine whether the driving state of the motor is in the prohibited area,
When the driving prohibition determining means determines that the driving state of the motor is within the prohibited area, the latch means holds the first determination result and keeps the first determination result until the main control device no longer outputs the motor driving signal. And the motor driving means inhibits driving of the motor when the latch means holds the first determination result.

Further, the apparatus further comprises a first counter for counting the time during which the drive prohibition determining means determines that the driving state of the motor is within the prohibited area, and the first counter counts for a first time. Is exceeded, the determination result of the drive inhibition determination means is transmitted to the latch means.
If the time counted by the counter is less than the first time, the determination result of the drive inhibition determination means is not transmitted to the latch means.

Further, the apparatus further comprises a current interrupting means for interrupting the current supply to the motor driving means, and a second counter for counting a time during which the latch means holds the first determination result. If the time counted by the counter exceeds the second time, the current supply to the motor is cut off by activating the current cutoff means, but if the time counted by the second counter is less than the second time, It is characterized in that the current interruption means is not operated.

Further, the drive prohibition judging means sets a prohibition region based on only the steering torque.

Further, the drive prohibition determining means sets a motor drive prohibition region based on a steering torque and a motor current.

Further, the drive prohibition determining means sets a motor drive prohibition region based on a steering torque and a vehicle speed.

Further, the driving prohibition determining means sets a motor driving prohibition region based on a steering torque, a motor current and a vehicle speed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram schematically showing a configuration of an electric power steering apparatus according to Embodiment 1 of the present invention. In FIG. 1, an electric power steering apparatus according to Embodiment 1 of the present invention includes a steering torque sensor 1 as a steering torque detecting means, a main control device 20, a sub-control device 30, a motor drive circuit 4 as a motor drive means, A motor current detection circuit 5 and a motor 6 are provided.

As shown in FIG. 1, the main controller 20
Includes a target current determination unit 21 and a motor current control unit 22. The target current determination unit 21 determines a target value of the current to be supplied to the motor 6 according to the value of the steering torque signal transmitted from the steering torque sensor 1.

The motor current controller 22 includes a motor current calculator 22a, logic gates 22b, 22c and 22.
d. The motor current calculation unit 22a determines which of left and right steering is to be assisted based on the target current value IMT transmitted from the target current determination unit 21, and in the case of left steering, sets the output DL1 to the H level. In the case of right steering, the output DR1 is set to the H level. Further, the motor current calculation unit 22a determines the duty ratio of the PWM signal supplied to the motor 6 based on the deviation between the target current IMT and the motor current IMD transmitted from the motor current detection circuit 5, and sets this as PWM1. Output.

Two-input one-output type logic gates 22b, 22
c and 22d are the outputs PW of the motor current calculator 22a.
M1, DL1 and DR1 are arranged to be inputted respectively, and when the main control device 20 is normal,
Functions as an AND gate. The logic gate 22
The other input terminals of b, 22c and 22d are configured to receive an output IL of the sub-control device 30 described later, and the output terminal is connected to the motor drive circuit 4. The logic gates 22b, 22c and 22d are
When an abnormality occurs in the main control device 20, the main control device 20 may not function normally (that is, does not function as an AND gate).

The sub-control unit 30 includes a motor drive prohibition determining unit 31 as drive prohibition determining means, an OR gate 32a,
A flip-flop (hereinafter, referred to as FF) 32b as a latch means and an inverter 32c are provided. The motor drive prohibition determining unit 31 determines a region where the passage of the motor current is prohibited in the characteristics of the motor current with respect to the steering torque (FIG. 16).
(See the hatched portion), and based on the motor current IMD transmitted from the motor current detection circuit 5 described later and the steering torque signal transmitted from the steering torque sensor 1,
This is for determining whether or not the driving state of the motor 6 is in the prohibited area. The output terminal of the motor drive inhibition determination unit 31 has an FF 32b and an inverter 32
c are connected in series.

The output terminals of the logic gates 22c and 22d are connected to the input terminal of the OR gate 32a. Further, the motor drive inhibition determination unit 31 and the OR gate 32a
Is connected to the input terminal of the FF 32b.
The output terminal of F32b is connected to the motor drive circuit 4 via the inverter 32c. The FF 32b holds the H level when receiving the H level Flag 1 from the motor drive prohibition determination unit 31, and once holds the H level signal, the FF 32b waits until receiving the L level signal from the OR gate 32a. , FF which are not cleared to the L level.

The motor drive circuit 4 includes an unillustrated 4
A motor drive unit 4a having a built-in bridge circuit composed of two FETs and AND gates 4b, 4c and 4d are provided. In the motor drive circuit 4 having such a structure, the output (DL3) of the AND gate 4c is at the H level (at the same time, DR3 is at the L level).
Level), the motor 6 is PWM-driven so as to assist left steering through the AND gate 4a.
When the output (DR3) of the gate 4d becomes H level, the motor 6 is PWM-driven so as to assist right steering. Further, the motor current detection circuit 5 constantly detects the motor current IMD supplied to the motor 6,
The signal representing the motor current IMD is transmitted to the motor current calculation unit 22a and the motor drive inhibition determination unit 31, as described above.

Next, the operation will be described. FIGS. 2 and 3 are flowcharts showing the control contents of the electric power steering apparatus according to Embodiment 1 of the present invention. FIG. 4 is a diagram illustrating characteristics of the motor current with respect to the steering torque.

As shown in FIG. 2, first, at step 20, a steering torque T is input from the steering torque sensor 1. Subsequently, at step 21, based on the steering torque T,
The driving direction of the motor and the target current IMT are determined. The target current IMT is specifically determined based on the characteristics shown in FIG. 4 and according to the vehicle speed detected by a vehicle speed sensor (not shown).

Then, in step 22, the motor current IMD detected by the motor current detection circuit 5 is input to the motor current calculator 22a. In step 23, the duty ratio of the PWM signal is determined in the motor current calculator 22a based on the difference between the target current IMT and the motor current IMD. The flow proceeds to step 24, where the motor current control unit 22 determines whether or not the output IL of the sub control device 30 is at the H level. If the output IL is not at the L level (if it is at the H level), the flow proceeds to step 25, and the driving direction of the motor 6 is determined.

If the driving direction of the motor 6 is a direction that assists the steering in the right direction, the flow proceeds to step 26, where the H level is set in DR2, the L level is set in DL2, and the PWM 2 is controlled by the motor current control unit. 22. On the other hand, if the driving direction of the motor 6 is a direction that assists steering in the left direction, the flow proceeds to step 26,
The L level is set to DR2 and the H level is set to DL2, and PWM2 is output from the motor current control unit 22 together with these signals.

If it is determined in step 24 that the output IL is at L level, DR2 and DL
2 are both set to L level, PWM2 is set to 0, and these are output from the main controller 20. The flow composed of the abnormal steps 20 to 29 is repeatedly performed in the main control device 20.

On the other hand, in the sub-control unit 30, first, as shown in FIG.
Flag2 is set to L level. Next step 31
Then, the steering torque T is input from the steering torque sensor 1. In step 32, the motor current IMD detected by the motor current detection circuit 5 is input to the prohibited area setting section 31 in the sub control device 30.

Further, the flow proceeds to step 33, where it is determined based on the steering torque T and the motor current IMD whether or not the driving state of the motor 6 is within the prohibited range.
If it is determined that the motor 6 is driven within the prohibited area, the flow proceeds to step 34, where DR2 and D
It is determined whether both L2 are at L level.

If it is determined in step 34 that both DR2 and DL2 are at the L level, the flow proceeds to step 35, in which Flag2 is set to the L level to inhibit driving of the motor 6, Further, the flow proceeds to step 37. If it is determined in step 34 that both DR2 and DL2 are not at the L level, the flow proceeds from step 34 to step 37.

On the other hand, if it is determined in step 33 that the driving state of the motor 6 is not within the prohibited area, the flow proceeds from step 33 to step 36,
The H level is set to Flag2, and the flow proceeds to step 37. In step 37, Flag2 is inverted, and in subsequent step 38, the determined Flag2 is output as the output IL of the sub control device 30.

Next, the contents of control on the side of the sub-control device 30 will be described with reference to FIG. FIG. 5 is a flowchart showing the control contents of the sub-control device of the electric power steering device according to Embodiment 1 of the present invention. As shown in FIG. 5, first, in step 51, the motor drive inhibition determination unit 31 determines whether the drive state of the motor 6 is within the inhibition area. If the motor 6 is being driven in the prohibited area, the flow proceeds to step 52, where the motor drive inhibition determination unit 31 sets the H level to Flag1, and the H level is held in the FF 32b.

The flow proceeds to step 54, where it is determined whether outputs DL2 and DL3 of logic gates 22c and 22d are both at the L level. Specifically, the OR of the outputs DL2 and DL3 is calculated by the OR gate 32a, and if both the outputs DL2 and DL3 are at the L level, the OR is calculated.
When the output of the level is transmitted from the OR gate 32a to the FF 32b, the H level signal held by the FF 32b is reset to the L level.
Is at the H level, O
Since the output of the H level is transmitted from the R gate 32a to the FF 32b, the H level held in the FF 32b is not cleared. Furthermore, the flow proceeds to step 55, and the H level is set to Flag2 by the FF 32b.

The flow proceeds to step 57, where the output IL of the sub-control device 30 is set to the L level for inhibiting the driving of the motor 6 in the inverter 32c.
As a result, as shown in FIG. 1, the L-level IL signal is transmitted to the AND gates 4b, 4c and 4d of the motor drive circuit, and the outputs of these AND gates are all at the L level. It is forbidden.

If it is determined in step 51 that the driving state of the motor 6 is not in the prohibition state, the flow proceeds to step 53, and the output of the motor driving prohibition determining section 31 to Flag1 is set to the L level. Is set. At this time, the FF 32b holds the signal at the L level. In step 56, the L-level signal held in the FF 32b is set to Flag2. Further, the flow proceeds to step 57, where the signal level is inverted by the inverter 32c, and the output I of the sub-control device 30 is output.
L becomes the H level at which the driving of the motor 6 is permitted.

When the H level IL signal is transmitted to the AND gates 4b, 4c and 4d of the motor drive circuit, the motor 6 is driven according to the output of the main control unit 20. That is, if DL3 transmitted from the main control device 20 is at H level (DR3 is at L level at the same time), the motor 6 assists left steering, and vice versa, the motor 6 assists right steering.

If the outputs DL2 and DR2 of the logic gates 22c and 22d are both at the L level in step 54, the output of the OR gate 32a is at the L level. The level is cleared to L level. The flow proceeds to step 56, where the L level is set to Flag2 as in the above-described case, and the output of the sub-control device 30 becomes the H level by being inverted by the inverter 32c. The motor 6 is driven according to the output of the main control device 20.

Based on the above control contents, in a practical operation state, for example, when the main control device is operating normally, the steering wheel is suddenly steered in the reverse direction, and the drive of the motor 6 is performed. If the state transitions into the prohibition region transiently, the motor drive prohibition determination unit 31 determines that the driving state of the motor 6 is in the prohibition region, and the flow shown in FIG. 42, and the FF 32b holds the H level.

The output IL of the sub-control device 30 is L
By setting to the level, the driving of the motor 6 is prohibited, and the motor current I
Since the MD decreases, the driving state of the motor 6 is no longer within the prohibited area, and the motor driving prohibition determining unit 31
Is set to L level. As a result, the FF 32b holds the L level, the output IL of the sub control device 30 is set to the H level, and the motor 6 is turned on in response to the output of the main control device 20.
Is driven.

On the other hand, when an abnormality has occurred in the main control unit 20, for example, when the driving state of the motor 6 enters the prohibited area due to, for example, suddenly turning the steering wheel in the reverse direction, When the motor drive prohibition determination unit 31 determines that the drive state of the motor 6 is within the prohibited area, the flow shown in FIG. 5 proceeds from step 51 to step 42, and the FF 32b holds the H level. When the output IL of the sub control device 30 is set to the L level, the driving of the motor 6 is prohibited.

Here, for example, the motor current control unit 22a of the main control unit 20 fails and the logic gate 22
Even though c or 22d functions as an OR gate or is short-circuited, at least one of DL2 or DR2 despite the fact that L-level IL signal is supplied from sub-control device 30 to logic gates 22c and 22d. Even if one of them is at the H level, the output of the OR gate 32b is at the H level, so the H level held in the FF 32b is not reset.

Therefore, in the electric power steering apparatus according to Embodiment 1 of the present invention, the driving state of the motor 6 is within the prohibited area, and the main control unit 20
DL2 and DR2 described above,
Until both are at the L level, that is, the main controller 20
However, the interlock by the sub-control device 30 can be maintained until the output of the drive signal of the motor 6 is stopped, so that the occurrence of a hunting phenomenon when the main control device 20 is abnormal can be prevented. Thus, it is possible to provide an electric power steering device having a high degree of safety.

In the above description, the case where the hunting phenomenon does not occur even when the driving state of the motor 6 enters the prohibited area when the main control device 20 is abnormal has been described. A hunting phenomenon can be similarly prevented even when the drive state of the motor 6 temporarily enters the prohibited area due to a change in the load of the motor when the control device 20 is operating normally. It is. Although the OR gate 32a, the FF 32b, and the inverter 32c are used as the logic gates on the sub-control device 30, the present invention is not limited to this mode as long as the same operation can be performed.

FIGS. 6 to 9 are graphs showing a prohibited area in the characteristic of the motor current with respect to the steering torque of the electric power steering apparatus according to Embodiment 1 of the present invention. The prohibition region when the motor drive prohibition determination unit 31 determines the drive state of the motor 6 may be set based on only the value of the steering torque as shown in FIG. 6, or as shown in FIG. The determination may be made based on the steering torque and the motor current. Although FIGS. 6 and 7 respectively show two types of characteristics (a, b), any characteristics may be used as long as such characteristics are obtained.

The prohibition region may be determined based on the steering torque and the vehicle speed as shown in FIG. 8, and further, as shown in FIG. It may be determined on the basis of. Note that, in the characteristics exemplarily shown in FIGS. 8 and 9, the prohibited area is set to be wider as the vehicle speed becomes higher.

Embodiment 2 FIG. 10 is a block diagram schematically showing a configuration of an electric power steering apparatus according to Embodiment 2 of the present invention. As shown in FIG. 10, an electric power steering apparatus according to Embodiment 2 of the present invention includes a sub-controller 30 having T1 as a first counter.
A counter 100 and a T2 counter 101 as a second counter are provided.

The T1 counter 100 is disposed between the motor drive prohibition judging section 31 and the FF 32b.
The time when the H level is set to g1 (that is, the motor 6
Time during which it is determined that the driving state of the motor is within the prohibited area)
Is a counter that counts T2 counter 1
01 is a counter that counts the time when the H level is set in Flag2 (that is, the time when the H level as the first level is held in the FF 32b). Note that the T2 counter 101 is connected to a relay (not shown) as a current interrupting unit provided in the motor drive circuit 4. When the output RY2 of the T2 counter 101 becomes L level, the relay in the motor drive circuit 4 is excited, and the current supply to the motor 6 is cut off.

The T1 counter 100 includes a counter section 100a and a comparing section 100b. The comparing section 100b compares the time counted by the counter section 100a with a predetermined time T1. If the counted time exceeds a predetermined time T1 as the first time, an H-level signal is output. If the counted time does not reach the predetermined time T1, an L-level signal is output.

Similarly, the T2 counter 101 includes a counter 101a, a comparator 101b, and an inverter 1
The comparison unit 101b compares the time counted by the counter unit 101a with a predetermined time T2 as a second time. If the counted time exceeds the predetermined time T2, the comparison unit 101b changes to the H level. A signal is output, and if it is less than the predetermined time T2, an L level signal is output. The comparison result of the comparison unit 100b is
The output is inverted by c.

Next, using the flowchart of FIG.
The operation of the electric power steering device according to Embodiment 2 of the present invention will be described. FIG. 11 is a flowchart showing control contents of the electric power steering device according to Embodiment 2 of the present invention. Since the operation of main control device 20 is the same as that of the first embodiment, only the operation of sub control device 30 will be described below. In FIG. 11, first, in step 110, the motor drive inhibition determination unit 31 determines whether the drive state of the motor 6 is within the inhibition area based on the steering torque T and the motor current IMD. If it is within the prohibited area, the motor drive prohibition determining section 31 outputs an H level signal.

The flow proceeds to step 111, where the T1 counter 100 counts the time during which the motor drive prohibition judging section 31 outputs the H-level signal. When the counted time exceeds the predetermined time T1, the flow proceeds to step 112, and the FF 32b stores H
By maintaining the level, the H level is set to Flag2, and the flow proceeds to step 113. On the other hand, if the counted time is less than the predetermined time T1 in step 111, the FF 32b does not operate, so that the flow proceeds to step 113 while Flag2 remains at the L level.

At step 113, it is determined whether or not outputs DL2 and DR2 of logic gates 22c and 22d are both at L level in OR gate 32a. When the outputs DL2 and DR2 are both at the L level, the output of the OR gate 32a is at the L level.
When the H-level signal held in F32b is cleared, in step 114, Flag2 is set to L-level. On the other hand, outputs DL2 and DR2
Are not at the L level, the flow proceeds to step 115 without clearing the contents held in the FF 32b.

In step 115, it is determined whether Flag2 is at H level. If it is at the H level, the flow proceeds to step 116, where Flag2 is inverted by the inverter 32c and the L level is set to IL, so that driving of the motor 6 is prohibited. In step 117, the T2 counter 101 sets the value of Flag2
It is determined whether or not the time when is at the H level has continued for a predetermined time T2 or more. That is, in the counter unit 101a, Fla
The time when g2 is at the H level is counted, and the comparison unit 10
In 1b, it is determined whether the counted time has exceeded a predetermined time T2.

If the time during which Flag2 is at the H level continues for a predetermined time T2 or more, the output of the comparison unit 101b becomes the H level, and the flow proceeds to step 118, where
The level is inverted by the inverter 101c, and R is demagnetized to demagnetize a relay (not shown) provided in the motor drive circuit 4.
Y2 is set to the L level, and the supply of the motor current is cut off.

On the other hand, if the predetermined time T2 is not reached, the flow returns to step 110 without setting RY2 to the L level. Therefore, the state where the motor current can be supplied is maintained. In step 115, F
If it is determined that flag2 is at the L level, the flow proceeds to step 119, the L level is inverted by the inverter 32c, IL is set to the level, and the motor 6 is controlled according to the control contents of the main controller 20. It will be driven.

Next, a specific operation of the electric power steering apparatus according to Embodiment 2 of the present invention will be described. FIGS. 12 to 14 are time charts showing specific operation states of the electric power steering apparatus according to Embodiment 2 of the present invention. FIG. 12 shows an operation state when noise occurs in the motor current IMD detected by the motor current detection circuit 5 due to a load change of the motor 6 when the steering wheel is steered to the left. .

In FIG. 12, when the motor current IMD exceeds a predetermined current value, the motor drive inhibition determining unit 31
When it is determined that the driving state of the motor 6 has entered the prohibited area, the count unit 100a of the T1 counter 100 counts the time during which Flag1 is at the H level. In this case, since the counted time is less than the predetermined time T1, the FF 32b is not held at the H level but remains at the L level. Therefore,
RY2 is held at the H level, and the state in which the motor current can be supplied continues.

FIG. 13 shows an operation state when the driving state of the motor 6 enters the prohibited area while the steering wheel is steered to the left. In FIG. 13, when the motor current IMD exceeds a predetermined current value and the motor drive inhibition determination unit 31 determines that the driving state of the motor 6 has entered the inhibition region, the count unit 100a of the T1 counter 100 sets Flag1 to Flag1. Is at H level. When the counted time exceeds the predetermined time T1, the FF 32b is held at the H level, and accordingly, the output I
L is at the L level. In addition, the time during which the FF 32b is held at the H level is counted by the T2 counter 101. In this case, since the counted time is less than the predetermined time T2, RY2 is held at the H level, and the motor current is supplied. The state where is possible continues.

FIG. 14 shows an operation state when the driving state of the motor 6 enters the prohibited area while the steering wheel is steered to the left. In FIG. 14, the driving state of the motor 6 enters the prohibited area, and as a result, the FF 32 b is maintained at the H level in FIG.
This is the same as the situation shown in FIG. In the situation shown in FIG.
Since the time during which F32b is maintained at the H level exceeds the predetermined time T2, RY2 is maintained at the L level when the predetermined time T2 elapses. As a result, the current supply to the motor 6 is cut off.

As described above, according to the electric power steering apparatus according to the second embodiment of the present invention, similarly to the electric power steering apparatus according to the first embodiment, when an abnormality occurs in main control apparatus 2, Even if it is determined that the drive state of the motor 6 has entered the prohibited area due to a change in the load of the motor 6 even though the control device 20 is normal, it is possible to suppress the occurrence of the hunting phenomenon.

Further, a T1 counter 100 and a T2 counter 101 are provided, and the FF 32b is set to the H level unless the state in which the drive state of the motor 6 has entered the prohibited area by the motor drive inhibition determination section 31 does not continue for a predetermined time T1 or more. In particular, although the main control device 20 is normal, the motor
When it is determined that the driving state of the motor 6 has entered the prohibited area, it can be determined with higher accuracy whether or not the driving of the motor 6 is prohibited.

Further, the Flag, which is the output of the FF 32b,
If the time during which the signal 2 is at the H level continues for a predetermined time T2 or more, the relay disposed in the motor drive circuit 4 is demagnetized. Supply can be cut off,
It is possible to prevent the motor 6 from being erroneously driven due to a malfunction of the main control device 20 or a malfunction of the motor drive circuit 4 itself, and to reliably prohibit the drive of the motor 6.

[0065]

According to the present invention, there is provided an electric power steering apparatus comprising: a steering torque detecting means for detecting a steering torque inputted to a steering wheel; and a main control means for controlling a motor based on the steering torque detected by the steering torque detecting means. A control device, a sub-control device that monitors the main control device, and a motor drive unit that drives the motor based on outputs of the main control device and the sub-control device, wherein the sub-control device determines a drive state of the motor A drive prohibition determination unit; and a latch unit that holds a first determination result of the drive prohibition determination unit. The drive prohibition determination unit is configured to prohibit the passage of the motor current in the characteristic of the motor current with respect to the steering torque. Is set, and it is determined whether the driving state of the motor is in the prohibited area.
When the drive prohibition determining means determines that the driving state of the motor is within the prohibition region, the first determination result is held and the first determination result is kept until the main control device no longer outputs the motor drive signal. The motor drive means holds the first determination result, and the motor drive means inhibits driving of the motor when the latch means holds the first determination result. As a result, an electric power steering apparatus having a high degree of safety can be provided.

Further, the apparatus further comprises a first counter for counting the time during which the drive prohibition determining means determines that the driving state of the motor is within the prohibited area, and the first counter counts the first time. Is exceeded, the determination result of the drive inhibition determination means is transmitted to the latch means.
If the time counted by the counter is less than the first time, the result of the determination by the drive inhibition determination means is not transmitted to the latch means. It is possible to provide an electric power steering device that can make a determination and has a high degree of safety.

Further, the apparatus further comprises a current interrupting means for interrupting the current supply to the motor driving means, and a second counter for counting a time during which the first determination result is held in the latching means. If the time counted by the counter exceeds the second time, the current supply to the motor is cut off by activating the current cutoff means, but if the time counted by the second counter is less than the second time, An electric power steering apparatus capable of determining whether or not to prohibit driving of a motor with higher accuracy, and reliably prohibiting driving of a motor because the current interrupting means is not operated. Can be provided.

Further, since the drive prohibition determining means sets the prohibition area based on only the steering torque, it is possible to determine with high accuracy whether or not to prohibit the driving of the motor. An electric power steering device can be provided.

Further, since the drive prohibition determining means sets the motor drive prohibition area based on the steering torque and the motor current, it is possible to determine with high precision whether or not to prohibit the drive of the motor. It is possible to provide an electric power steering device that can perform the operation.

Further, the drive prohibition determining means sets the motor drive prohibition region based on the steering torque and the vehicle speed, so that it is possible to determine with high accuracy whether to prohibit the drive of the motor. And an electric power steering device capable of performing such operations.

The drive prohibition determining means sets the motor drive prohibition region based on the steering torque, the motor current and the vehicle speed. It is possible to provide an electric power steering device that can perform the operation with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an electric power steering apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing control contents of the electric power steering device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing control contents of the electric power steering device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating characteristics of a motor current with respect to a steering torque.

FIG. 5 is a flowchart showing control contents of a sub control device of the electric power steering device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a forbidden region in a characteristic of a motor current with respect to a steering torque of the electric power steering device according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a forbidden region in a characteristic of a motor current with respect to a steering torque of the electric power steering device according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a forbidden region in a characteristic of a motor current with respect to a steering torque of the electric power steering device according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating a forbidden region in a characteristic of a motor current with respect to a steering torque of the electric power steering device according to the first embodiment of the present invention.

FIG. 10 is a block diagram schematically showing a configuration of an electric power steering apparatus according to Embodiment 2 of the present invention.

FIG. 11 is a flowchart showing control contents of the electric power steering device according to Embodiment 2 of the present invention.

FIG. 12 is a time chart showing a specific operation state of the electric power steering device according to Embodiment 2 of the present invention.

FIG. 13 is a time chart illustrating a specific operation state of the electric power steering device according to Embodiment 2 of the present invention.

FIG. 14 is a time chart showing a specific operation state of the electric power steering device according to Embodiment 2 of the present invention.

FIG. 15 is a block diagram conceptually showing a configuration of a conventional electric power steering device.

FIG. 16 is a characteristic diagram illustrating a relationship between a steering torque detected by a steering torque sensor and a steering torque signal output by the steering torque sensor.

[Explanation of symbols]

Reference Signs List 1 steering torque sensor (steering torque detecting means), 4 motor drive circuit (motor drive means), 6 motors, 20
Main control device, 30 sub-control device, 31 motor drive prohibition determining section (motor drive prohibition determining means), 32b FF
(Latch means), 100 T1 counter (first counter), 101 T2 counter (second counter).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D032 CC26 CC35 CC42 DA15 DA23 DA64 DC07 DC09 DC33 DC34 DD10 DD17 DE09 EA01 EB11 EC23 GG01 3D033 CA03 CA13 CA16 CA20 CA21 CA32

Claims (7)

[Claims] 1. A steering torque detecting means for detecting a steering torque input to a steering wheel; a main control device for controlling driving of a motor based on a steering torque detected by the steering torque detecting means; A sub-control device that monitors the output of the main control device and the sub-control device, and a motor drive unit that drives a motor based on the outputs of the main control device and the sub-control device. Latch means for holding a first determination result of the drive inhibition determination means, wherein the drive inhibition determination means sets a prohibited area in which the passage of the motor current is prohibited in the characteristics of the motor current with respect to the steering torque. And determining whether the driving state of the motor is in the prohibited area. When it is determined that the drive state of the motor is within the prohibited area, the first determination result is held, and the first determination result is held until the main control device stops outputting the motor drive signal. An electric power steering apparatus, wherein the motor driving unit prohibits driving of the motor when the latch unit holds the first determination result. 2. The apparatus according to claim 1, further comprising: a first counter for counting a time during which the drive state of the motor is determined to be within the prohibited area by the drive inhibition determination means, wherein the first counter counts the first time. If the time exceeds the time, the result of the determination by the drive inhibition determination means is transmitted to the latch means, but if the time counted by the first counter is less than the first time, the determination result of the drive inhibition determination means is changed to The electric power steering apparatus according to claim 1, wherein the electric power steering apparatus does not transmit the electric power to the latch means. 3. A current interrupting means for interrupting a current supply to said motor driving means, and said first means is provided in said latch means.
And a second counter that counts a time during which the determination result is held. When the time counted by the second counter exceeds a second time, the current cutoff unit is operated to control the motor. Cut off the current supply,
The electric power steering device according to claim 1 or 2, wherein the current interrupting means is not operated unless the time counted by the second counter is less than the second time. 4. The electric power steering control device according to claim 1, wherein the drive prohibition determination unit sets the prohibition region based only on a steering torque. 5. The electric power steering system according to claim 1, wherein the drive prohibition determining unit sets a motor drive prohibition region based on a steering torque and a motor current. Control device. 6. The electric power steering control according to claim 1, wherein the drive prohibition determining unit sets a motor drive prohibition region based on a steering torque and a vehicle speed. apparatus. 7. The driving prohibition determining means includes: a steering torque;
The electric power steering control device according to any one of claims 1 to 3, wherein a motor drive inhibition region is set based on the motor current and the vehicle speed.